Yes, they maintain prioritized links between their datacenters, many of which are fully private. However, the Warp free plan simply bounces to the nearest CF datacenter which participates in Warp (not all of their centers do) and then back into the public internet, though it's through their massive pipe. Warp+ uses their Argo routing through their private backbone to get you as close to the origin as possible within the Warp network.